Vapor provision device with liquid capture

ABSTRACT

An assembly for a vapor provision device includes a reservoir for storing source liquid; a liquid conduit for delivering the source liquid from the reservoir to a vapor generator for vaporizing the source liquid; and a liquid capture element in liquid transfer contact with at least a portion of the liquid conduit between the vapor generator and a part of the liquid conduit that receives liquid from the reservoir, and including an absorbent structure providing a higher capillary force than a capillary force of the reservoir.

PRIORITY CLAIM

The present application is a continuation of application Ser. No.16/489,147, filed Aug. 27, 2019, which in turn is a National Phase entryof PCT Application No. PCT/GB2018/050505, filed Feb. 27, 2018, which inturn claims priority from GB Patent Application No. 1703284.8, filedMar. 1, 2017, each of which is hereby fully incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to vapor provision devices such aselectronic vapor provision devices, and assemblies for vapor provisiondevices such as electronic vapor provision devices.

BACKGROUND

Aerosol or vapor provision devices and systems such as e-cigarettesgenerally comprise a reservoir of a source liquid containing aformulation, typically including nicotine, from which an aerosol isgenerated, such as through vaporization or other means. Thus an aerosolsource for a vapor provision system may comprise a heating element orother vapor generating component coupled to a portion of the sourceliquid from the reservoir. In some systems, the heating element andreservoir are comprised within a first section or component which isconnectable to a second section or component housing a battery toprovide electrical power to the heating element. This first section maybe referred to as a cartomizer, and can be disposable to be replacedwhen the source liquid has been consumed. In use, a user inhales on thedevice to activate the heating element which vaporizes a small amount ofthe source liquid, which is thus converted to an aerosol for inhalationby the user.

The reservoir may hold free-flowing source liquid or may house someabsorbent material which is soaked in source liquid. The reservoir isdesigned so that the source liquid can exit the reservoir, reach theheating element and be vaporized when the heating element is at a hightemperature; this may be by use of a conduit such as a porous wickingelement which reaches into the reservoir and is physically coupled tothe heating element. While the reservoir and conduit are constructed tocontain the source liquid and deliver it for vaporization at anappropriate rate, this arrangement can be very sensitive to pressuredifferentials between the reservoir interior and the externalenvironment. An increase in pressure inside the tank relative to theenvironment can force liquid out of the reservoir until sufficientliquid is lost to re-establish a pressure balance. The escaped liquidmay be too much for the conduit and heater to successfully hold orvaporize, and so may leak into the interior of the device, potentiallycausing damage and ultimately leakage from the device itself, and alsoloss of liquid that could otherwise be consumed.

Approaches aimed at mitigating these problems are of interest.

SUMMARY

According to a first aspect of certain embodiments described herein,there is provided an assembly for a vapor provision device comprising: avapor generator for vaporizing source liquid; a liquid conduit fordelivering source liquid from a reservoir to the vapor generator; and aliquid capture element in liquid transfer contact with at least aportion of the liquid conduit between the vapor generator and a part ofthe liquid conduit that receives liquid from the reservoir, andcomprising an absorbent structure providing a lower capillary force thana capillary force of the liquid conduit.

According to a second aspect of certain embodiments described herein,there is provided a cartridge assembly for a vapor provision devicecomprising an assembly according to the first aspect, and a reservoirfor holding source liquid.

According to a third aspect of certain embodiments described herein,there is provided a vapor provision device comprising an assemblyaccording to the first aspect or a cartridge assembly according to thesecond aspect.

According to a fourth aspect of certain embodiments, there is providedan atomizer assembly for an electronic vapor provision devicecomprising: a vaporizer for vaporizing source liquid; a liquid deliverymechanism for delivering source liquid from a reservoir to thevaporizer; and an absorbent buffer element contacting the liquiddelivery mechanism between an outlet of the reservoir and the vaporizerand being less hydrophilic to the source liquid than the liquid deliverymechanism.

According to a fifth aspect of certain embodiments, there is provided amethod for capturing source liquid that has leaked from a reservoir in avapor provision device, the method comprising: arranging a liquidcapture element in liquid transfer contact with at least a portion of aliquid conduit configured to deliver source liquid from a reservoir to avapor generator, the portion lying between the vapor generator and apart of the liquid conduit that receives liquid from the reservoir,wherein the liquid capture element comprises an absorbent structureproviding a lower capillary force than a capillary force of the liquidconduit.

These and further aspects of certain embodiments are set out in theappended independent and dependent claims. It will be appreciated thatfeatures of the dependent claims may be combined with each other andfeatures of the independent claims in combinations other than thoseexplicitly set out in the claims. Furthermore, the approach describedherein is not restricted to specific embodiments such as set out below,but includes and contemplates any appropriate combinations of featurespresented herein. For example, an electronic vapor provision device or acomponent for an electronic vapor provision device may be provided inaccordance with approaches described herein which includes any one ormore of the various features described below as appropriate.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments will now be described in detail by way of exampleonly with reference to the accompanying drawings in which:

FIG. 1 shows a simplified schematic cross-sectional view of an exampleelectronic cigarette or vapor provision device.

FIG. 2 shows a schematic cross-sectional view of a first example aerosolsource of an electronic cigarette, comprising a reservoir and anatomizer.

FIG. 3 shows a schematic cross-sectional view of a second exampleaerosol source of an electronic cigarette, comprising a reservoir and anatomizer;

FIG. 4 shows a schematic cross-sectional view of a third example aerosolsource of an electronic cigarette, comprising a reservoir and anatomizer.

FIG. 5 shows a schematic longitudinal cross-sectional view of an exampleaerosol source incorporating a liquid buffer.

FIG. 6 shows a schematic longitudinal cross-sectional view of a furtherexample aerosol source incorporating a liquid buffer.

FIG. 7 shows a schematic transverse cross-sectional view of an exampleaerosol source incorporating a liquid buffer.

FIG. 8 shows a schematic transverse cross-sectional view of anotherexample aerosol source incorporating a liquid buffer.

DETAILED DESCRIPTION

Aspects and features of certain examples and embodiments arediscussed/described herein. Some aspects and features of certainexamples and embodiments may be implemented conventionally and these arenot discussed/described in detail in the interests of brevity. It willthus be appreciated that aspects and features of apparatus and methodsdiscussed herein which are not described in detail may be implemented inaccordance with any conventional techniques for implementing suchaspects and features.

As described above, the present disclosure relates to (but is notlimited to) electronic aerosol or vapor provision systems, such ase-cigarettes. Throughout the following description the terms“e-cigarette” and “electronic cigarette” may sometimes be used; however,it will be appreciated these terms may be used interchangeably withaerosol (vapor) provision system or device. Similarly, “aerosol” may beused interchangeably with “vapor”.

As used herein, the term “component” is used to refer to a part,section, unit, module, assembly or similar of an electronic cigarettethat incorporates several smaller parts or elements, often within anexterior housing or wall. An electronic cigarette may be formed or builtfrom one or more such components, and the components may be removablyconnectable to one another, or may be permanently joined together duringmanufacture to define the whole electronic cigarette.

According to some embodiments of the disclosure, it is proposed toprovide an electronic cigarette with a liquid buffer system that canreceive (capture) and store excess liquid, for example arising from arelative overpressure in a liquid reservoir that forces more liquid outof the reservoir than can be held in a wicking element or be vaporized.An absorbent buffer element is arranged in contact with the liquidsystem that delivers liquid from the reservoir to a vapor generatingelement, but is configured such that under normal operation it will notabsorb liquid, yet is available to absorb excess liquid that mightotherwise leak into the interior of the electronic cigarette. If thereservoir becomes empty, any liquid held in the buffer element may thenbe supplied for vaporization. Hence, escaped liquid need not be wasted,and is less likely to leak into the device interior or out from theelectronic cigarette. In effect, leaked liquid is retained within astorage system separate from the reservoir as usable liquid followingsome leakage failure modes. Loss of consumable liquid is thereforereduced, and external leaks are reduced, giving increased userconvenience.

FIG. 1 is a highly schematic diagram (not to scale) of an exampleaerosol/vapor provision system such as an e-cigarette 10. Thee-cigarette 10 has a generally cylindrical shape, extending along alongitudinal axis indicated by a dashed line, and comprises two maincomponents, namely a control or power component or section 20 and acartridge assembly or section 30 (sometimes referred to as a cartomizer,clearomizer or atomizer) that operates as a vapor generating component.

The cartridge assembly 30 includes a reservoir 3 containing a sourceliquid comprising a liquid formulation from which an aerosol is to begenerated, for example containing nicotine. As an example, the sourceliquid may comprise around 1 to 3% nicotine and 50% glycerol, with theremainder comprising roughly equal measures of water and propyleneglycol, and possibly also comprising other components, such asflavorings. The reservoir 3 has the form of a storage tank, being acontainer or receptacle in which source liquid can be stored such thatthe liquid is free to move and flow within the confines of the tank.Alternatively, the reservoir 3 may contain a quantity of absorbentmaterial such as cotton wadding or glass fiber which holds the sourceliquid within a porous structure. The reservoir 3 may be sealed afterfilling during manufacture so as to be disposable after the sourceliquid is consumed, or may have an inlet port or other opening throughwhich new source liquid can be added. The cartridge assembly 30 alsocomprises an electrical heating element or heater 4 located externallyof the reservoir tank 3 for generating the aerosol by vaporization ofthe source liquid by heating. A liquid conduit arrangement such as awick or other porous element 6 may be provided to deliver source liquidfrom the reservoir 3 to the heater 4. The wick 6 has one or more partslocated inside the reservoir 3 so as to be able to absorb source liquidand transfer it by wicking or capillary action to other parts of thewick 6 that are in contact with the heater 4. This liquid is therebyheated and vaporized, to be replaced by new source liquid transferred tothe heater 4 by the wick 6. The wick therefore extends through a wallthat defines the interior volume of the reservoir tank 3, and might bethought of as a bridge, path or conduit between the reservoir 3 and theheater 4 that delivers or transfers liquid from the reservoir to theheater. Terms including conduit, liquid conduit, liquid transfer path,liquid delivery path, liquid transfer mechanism, and liquid deliverymechanism may all be used interchangeably herein to refer to a wick orcorresponding component or structure.

A heater and wick (or similar) combination is sometimes referred to asan atomizer or atomizer assembly, and the reservoir with its sourceliquid plus the atomizer may be collectively referred to as an aerosolsource. Other terminology may include a liquid delivery assembly, aliquid transfer assembly, or simply assembly, where in the presentcontext these terms may be used interchangeably to refer to a vaporgenerating element (vapor generator) and a wicking or similar componentor structure (liquid conduit) that delivers or transfer liquid from areservoir to the vapor generator. Various designs are possible, in whichthe parts may be differently arranged compared to the highly schematicrepresentation of FIG. 1 . For example, the wick 6 may be an entirelyseparate element from the heater 4, or the heater 4 may be configured tobe porous and able to perform the wicking function directly (a metallicmesh, for example). Alternatively, the liquid conduit may be formed fromone or more slots, tubes or channels between the reservoir and theheater which are narrow enough to support capillary action to drawsource liquid out of the reservoir and deliver it for vaporization.Other means for vapor generation may be used in place of a heater, sucha vibrating vaporizer based on the piezoelectric effect, for example. Inan electrical or electronic device, the vapor generator may be anelectrical heating element that operates by ohmic (Joule) heating or byinductive heating. Also, the device may a non-electrical device, thatoperates by pump-action, for example. In general, therefore, an atomizercan be considered to be a vapor generating or vaporizing element able togenerate vapor from source liquid delivered to it, and a liquid conduitable to deliver or transport liquid from a reservoir or similar liquidstore to the vapor generator by a capillary force. Embodiments of thedisclosure are applicable to all and any such assembly configurations.Regardless of the implementation, the parts will be configured to form aliquid flow path by which the source liquid is able to travel from theinterior of the reservoir 3 to the vicinity and surface of the heater 4(or other vapor generator) for vaporization. This is the intended fluidpath, whereby liquid is delivered to the heater and should besuccessfully vaporized and thereby prevented from arriving at anyunwanted location elsewhere within the electronic cigarette. Thisoperation is based on a delivery of source liquid at an expected ratesuch that the vapor generator can handles the incoming liquid. However,in the event of a leakage such as may be caused by excess pressureinside the reservoir, or even under normal pressure conditions when thevapor generator is not operating, too much liquid may accumulate in orat the conduit and the vapor generator and drip away to escape as freeliquid in a chamber housing the atomizer.

Returning to FIG. 1 , the cartridge assembly 30 also includes amouthpiece 35 having an opening or air outlet through which a user mayinhale the aerosol generated by the heater 4.

The power component 20 includes a cell or battery 5 (referred to hereinafter as a battery, and which may be re-chargeable) to provide power forelectrical components of the e-cigarette 10, in particular the heater 4.Additionally, there is a printed circuit board 28 and/or otherelectronics or circuitry for generally controlling the e-cigarette. Thecontrol electronics/circuitry connect the heater 4 to the battery 5 whenvapor is required, for example in response to a signal from an airpressure sensor or air flow sensor (not shown) that detects aninhalation on the system 10 during which air enters through one or moreair inlets 26 in the wall of the power component 20. When the heatingelement 4 receives power from the battery 5, the heating element 4vaporizes source liquid delivered from the reservoir 3 by the wick 6 togenerate the aerosol, and this is then inhaled by a user through theopening in the mouthpiece 35. The aerosol is carried from the aerosolsource to the mouthpiece 35 along an air channel (not shown) thatconnects the air inlet 26 to the aerosol source to the air outlet when auser inhales on the mouthpiece 35. An air flow path through theelectronic cigarette is hence defined, between the air inlet(s) (whichmay or may not be in the power component) to the atomizer and on to theair outlet at the mouthpiece. In use, the air flow direction along thisair flow path is from the air inlet to the air outlet, so that theatomizer can be described as lying downstream of the air inlet andupstream of the air outlet.

In this particular example, the power section 20 and the cartridgeassembly 30 are separate parts detachable from one another by separationin a direction parallel to the longitudinal axis, as indicated by thesolid arrows in FIG. 1 . The components 20, 30 are joined together whenthe device 10 is in use by cooperating engagement elements 21, 31 (forexample, a screw or bayonet fitting) which provide mechanical andelectrical connectivity between the power section 20 and the cartridgeassembly 30. This is merely an example arrangement, however, and thevarious components may be differently distributed between the powersection 20 and the cartridge assembly section 30, and other componentsand elements may be included. The two sections may connect togetherend-to-end in a longitudinal configuration as in FIG. 1 , or in adifferent configuration such as a parallel, side-by-side arrangement.The system may or may not be generally cylindrical and/or have agenerally longitudinal shape. Either or both sections may be intended tobe disposed of and replaced when exhausted (the reservoir is empty orthe battery is flat, for example), or be intended for multiple usesenabled by actions such as refilling the reservoir and recharging thebattery. Alternatively, the e-cigarette 10 may be a unitary device(disposable or refillable/rechargeable) that cannot be separated intotwo parts, in which case all components are comprised within a singlebody or housing. Embodiments and examples of the present disclosure areapplicable to any of these configurations and other configurations ofwhich the skilled person will be aware.

The example device in FIG. 1 is presented in a highly schematic format.FIGS. 2 and 3 show more detailed representations of aerosol sourcesaccording to examples, indicating relative positions of a tank, a heaterand a wick.

FIG. 2 shows a cross-sectional side view of an example aerosol source. Areservoir tank 3 has an outer wall 32 and an inner wall 34, each ofwhich is generally cylindrical. The inner wall 34 is centrally disposedwithin the outer wall 32 to define an annular space between the twowalls; this is the interior volume of the tank 3 intended to hold sourceliquid. The tank is closed at its lower end (in the orientationdepicted) by a bottom wall 33 and at its top end by an upper wall 36.The central space encompassed by the inner wall 34 is a passage orchannel 37 which at its lower end receives air drawn into the electroniccigarette (such as via air intakes 26 shown in FIG. 1 ), and at itsupper end delivers aerosol for inhalation (such as through themouthpiece 35 in FIG. 1 ). It also defines a chamber housing theatomizer.

Disposed within the airflow channel 37 is an atomizer 40 comprising aheater 4 and a wick 6. The wick, an elongate porous element that in thisexample is rod-shaped and may be formed from fibers, is arranged acrossthe airflow passage (shown as closer to the lower end of the tank 3, butit may be positioned higher) so that its ends pass through apertures inthe inner wall 34 and reach into the interior volume of the tank 3 toabsorb source liquid therein. The heater 4 is an electrically poweredheating element in the form of a wire coil wrapped around the wick 6.Connecting leads 4 a, 4 b join the heater to a circuit (not shown) forthe provision of electrical power from a battery. The aerosol sourcewill be disposed within the housing of a cartridge assembly section ofan electronic cigarette, with a mouthpiece arranged at its top end and acontroller and battery arranged at its lower end (possibly in aseparable component). Note that the outer wall 32 of the tank 3 may ormay not also be a wall of the cartridge assembly housing. If these wallsare shared, the cartridge assembly may be intended to be disposable whenthe source liquid has been consumed, to be replaced by a new cartridgeassembly connectable to an existing battery/power section, or may beconfigured so that the reservoir tank 3 can be refilled with sourceliquid. If the tank wall and the housing wall are different, the tank 3or the whole aerosol source may be replaceable within the housing whenthe source liquid is consumed, or may be removable from the housing forthe purpose of refilling. These are merely example arrangements and arenot intended to be limiting.

In use, when the aerosol source within its assembly housing is joined toa battery section (separably or permanently depending on the e-cigarettedesign), and a user inhales through the mouthpiece, air drawn into thedevice through an inlet or inlets enters the airflow channel 37. Theheater 4 is activated to produce heat; this causes source liquid broughtto the heater 4 by the wick 6 to be heated to vaporization. The vapor iscarried by the flowing air further along the airflow channel 37 to themouthpiece of the device to be inhaled by the user. The arrows Aindicate the airflow and its direction along the air flow path throughthe device.

FIG. 3 shows a cross-sectional side view of a further example aerosolsource, in which the atomizer is positioned below a tank 3, which is notannular. The wick 6 has a u-shape, with its two ends positioned insidethe tank 3 via apertures in a base wall 33 of the tank 3. As in FIG. 2 ,the heater 4 is a wire coil wrapped around a central portion of thewick. Air A can enter a chamber 7 below the tank housing the coil 4 andthe wick 6 (an atomizer chamber), collect vaporized liquid as it flowsover the heater, and then leaves the chamber 7 to travel along a furtherairflow path (not shown) to a mouthpiece of the device.

FIG. 4 shows a cross-sectional side view of an alternative exampleaerosol source. As in the FIG. 2 example, the tank 3 is an annular spaceformed between an outer wall 32 and an inner wall 34, with the interiorspace of the tubular inner wall 34 providing an airflow channel 37. Inthis example, however, the rod-shaped wick and coiled heating elementare replaced by an atomizer 40 in which a single entity or elementprovides both the wicking and heating functions. An electricallyconductive mesh can be used for this, for example, where the conductivecharacteristic allows the atomizer to receive electrical power and heatup, while the mesh structure allows a wicking action. The atomizer 40 isagain arranged across the airflow channel 37 with parts passing throughslots or other apertures in the inner wall 34 into the interior volumeof the tank 3. The slots may be arranged as narrow openings to providesome capillary force to contribute to drawing liquid out of thereservoir, or may be sealed around the heating element 40 so thatcapillary action arises from the pores of the mesh of the heatingelement 40 only. In this example, the atomizer 40 has an elongate planarconfiguration and is arranged such that its long edges reach into thereservoir, and its short ends are at each end of the airflow passage 37.These ends 4 a, 4 b are connected to a battery by appropriatearrangement of electrical conductors (not shown). Thus, a larger area ofvaporizing surface is offered to air flowing through the airflowchannel.

In all these examples, the apertures through which the liquid leaves thereservoir to be conducted by the liquid conduit to the vapor generatormay be sealed to some extent to minimize source liquid leakage from thetank 3 into the airflow channel 37 or atomizer chamber 7; neverthelessleakage may still arise, such as in the event of pressure inside thetank exceeding the external pressure. Also, FIGS. 2 to 4 are merelyexamples of aerosol sources to illustrate various alternatives availablefor achieving aerosol generation. Other configurations can achieve thesame effect, and the disclosure is not limited in this regard. Inparticular, the reservoir may have other formats and the liquid couplingbetween the reservoir and the atomizer may differ. Whicheverconfiguration is adopted, any design which includes a reservoir in theform of a tank, container, receptacle or similar volume for holding thesource liquid will be potentially vulnerable to unwanted leakage of anexcess of source liquid from the reservoir via the liquid transfer pathleading to the atomizer. Liquid may begin its journey along the intendedpath for vaporization and arrive at or near the heater, but then not bevaporized. This may happen if, for example, the wicking action drawsliquid towards the heater at a faster rate than it can be vaporized bythe heater when activated, or if a pressure differential forces liquidout of the reservoir at a faster than intended rate, or when wickingcontinues when the heater is not activated. Liquid can then accumulatein or near the atomizer beyond the amount which can be held in theporous structure of the liquid conduit and/or the vaporizer (dependingon construction), i.e. the liquid conduit and the vaporizer may becomesaturated, and the liquid may then be released as free liquid into theairflow channel, creating an unwanted escape or leak of liquid.

A potential technique to address unwanted leaks is to minimize leakagefrom the reservoir apertures, for example by including some form ofseal. However, it is not desirable to provide a completely sealedreservoir, since it would be airtight or near-airtight and thereforerestrict air from entering the reservoir. An ingress of air is necessaryto equalize the pressure inside the reservoir as the source liquid isconsumed, and to allow the continued outward flow of source liquid tothe atomizer. Also, it is necessary to maintain the openings throughwhich the liquid leaves the reservoir to reach the atomizer, andcapillary action will continue to draw liquid to the atomizer if theheater is activated for vaporization or not.

Accordingly, an alternative approach is proposed to address loss ofsource liquid. It is proposed to arrange for capture or collection ofany excess liquid in a manner that allows it to be consumed at a latertime. Use of a liquid buffer element comprising an absorbent material isproposed.

A liquid buffer is formed from an absorbent material, which is able toabsorb incident source liquid under certain conditions. The liquidbuffer is arranged within an electronic cigarette or a component of anelectronic cigarette which houses an atomizer in such a way that it isin liquid transfer contact with the liquid conduit (liquid transferpath) carrying liquid from the reservoir to the vapor generator. Thecontact between the buffer and the conduit is positioned at a part ofthe conduit that lies between a part or parts of the conduit thatreceive liquid from the reservoir (for example, end parts of the wicksof the FIGS. 2 and 3 examples that lie inside the reservoir) and thelocation where the conduit meets the vapor generator (for example, theheating coil in the FIGS. 2 and 3 examples). Hence, the buffer elementcontacts the conduit along the path taken by liquid moving from thereservoir to the vaporizer. By “liquid transfer contact” it is meantthat the liquid buffer and the liquid conduit are placed in sufficientproximity that liquid can transfer one from the other; this may or maynot include actual physical contact or touching.

The liquid buffer or liquid buffer element provides a buffering functionbetween the liquid conduit and other regions within and outside theelectronic cigarette, to address leakage. Leaked liquid is therebycaptured by the buffer, and moreover can be stored therein for laterconsumption; accordingly this part may be considered as a liquid captureelement, or liquid storage element. These various terms may be usedinterchangeably herein.

The absorbent material(s) from which the liquid buffer is formed arechosen with particular regard to the absorbent property. It is desiredthat under normal conditions, namely when the amount of liquid held inthe liquid conduit is below a saturation threshold and so does notproduce a leak of free liquid, the buffer does not absorb significantamounts of liquid from the conduit. In other words, liquid is drawnalong the conduit directly from reservoir to vaporizer without beingdrawn into the liquid buffer, despite the liquid transfer contactbetween the buffer and the conduit.

However, an overpressure situation in the reservoir may result in moreliquid being forced into the conduit than the capillary force andsurface tension it offers can hold. The conduit thus becomes saturated,and excess liquid may present as free liquid at a surface of theconduit. The buffer element is in place to absorb this free liquid, andprevent it from escaping to elsewhere within or outside the electroniccigarette.

This is achieved by forming the liquid buffer from an absorbentstructure that provides a lower capillary force than the capillary forceoffered by the liquid conduit (be it a porous wick, or a capillarychannel, slot or tube). Under normal conditions, the higher capillaryforce of the conduit will maintain fluid within the conduit inpreference to the buffer. If the conduit becomes saturated, free liquidis then able to escape the capillary force of the conduit, but may thenbe taken up by the capillary force of the buffer instead. The liberatedliquid is hence held in the buffer.

If the leak failure mode is subsequently rectified, such as by thepressures in the tank and the surrounding environment equalizing, theconduit can return to its proper operation and hold the amount of liquidgoverned by its capillary force and surface tension. A steady state isresumed, and liquid is delivered to the vapor generator at anappropriate rate. For as long as there is liquid remaining in the tank,the conduit will advantageously absorb liquid from the tank as comparedto the buffer, because the buffer material has a higher capillary forcethan the tank (which in the case of a free liquid reservoir offers ineffect a zero capillary force). Hence, liquid is properly delivered forvaporization, and the buffer continues to store any liquid it collectedduring the leakage episode.

When the reservoir becomes empty and can no longer feed any liquid tothe conduit, the conduit is then able to reabsorb liquid from thebuffer, and deliver this to the vapor generator. Hence, liquid whichwould otherwise have been lost during the leakage episode is able to beconsumed. At least some of any liquid stored in the buffer will be ableto be regained in this way. Thus, not only is lost liquid prevented fromdamaging or escaping from the electronic cigarette, it is also retainedfor future consumption, thereby reducing waste. The buffer acts as partof the overall liquid accommodation in the electronic cigarette; it is asupplement to and separate from the reservoir.

As noted above, the buffer is made from an absorbent structure whichprovides a lower capillary force to the source liquid than the capillaryforce of the conduit that delivers the source liquid from the reservoirto the vapor generator. Hence, the absorbent structure is implementedwith reference to the nature and properties of the conduit. These willinclude the width of slots, channels, tubes and pipes in the case of aconduit having the form of openings within the electronic cigarettestructure. For a conduit formed from a porous material, such as wickformed from fibers (cotton fibers or glass fibers for example) or aporous ceramic, the pore size and density are relevant. Hence, thebuffer may comprise an absorbent material having a lower density thanthe conduit, and/or a higher porosity (ratio of pore/void volume tototal volume) than the conduit. The size (width or diameter) of thepores is also of interest since this will also affect the capillaryforce offered by a material. Using these characteristics to select anabsorbent buffer structure with a lower capillary force than the conduitmeans that under normal operation (when the conduit is not saturated)the capillary forces offered by the buffer and the conduit will favorcapillary movement of liquid from the tank to the vaporizer as theliquid is drawn into the smaller capillary spaces. There is insufficientcapillary force within the absorbent buffer structure to draw liquid outof the conduit, so the buffer does not absorb significant amounts ofliquid under normal circumstances.

The buffer may be formed from a dedicated absorbent material. Examplesof materials which are suitable for use as a liquid buffer includenatural sponge, synthetic sponge, porous ceramic, cotton wadding, glassfiber wadding, wool, porous plastics materials, structure made from orcomprising porous polymer fibers, and structures made from non-wovenfibers. Such materials have a porosity and density that providecapillary force, which can be compared to that of the conduit andselected to be lower.

Alternatively, the liquid buffer may comprise a capillary structureoffering an appropriate level of capillary force, where the capillarystructure or network is one or more connected or unconnected slots,channels, tubes, openings and similar in, for example, a part of theelectronic cigarette such as a side wall, or other rigid/solidcomponent, rather than being formed from a separate piece of absorbentmaterial. So, in an example, both the conduit and the buffer maycomprise one or more capillary channels, where the conduit channels arenarrower than the buffer channels to provide the required highercapillary force.

Hence, the liquid buffer may be thought of as an absorbent structure,where the absorbency may be provided by a dedicated absorbent materialor by capillary holes in a suitable component. Unless indicated by thecontext, the terms “absorbent material” and “absorbent structure” may beused interchangeably in the present disclosure.

In summary, either or both of the conduit and the buffer may comprise acapillary network of capillary channel(s) in a solid component of theelectronic cigarette, or a dedicated absorbent material. Allcombinations of these options are viable.

To achieve the required absorbent operation, the liquid conduit may havean average or characteristic capillary pore size that is smaller than anaverage or characteristic capillary pore size of the absorbent structureor material from which the liquid buffer is formed. As an example, alargest capillary pore size of the liquid conduit may be smaller thanthe smallest capillary pore size of the absorbent structure.

One may also consider the buffer in terms of its relative hydrophilia orhydrophobia (or corresponding terms for a non-water-based sourceliquid). The buffer can comprise an absorbent material or structurewhich is more hydrophobic or less hydrophilic than the liquid conduit.Conversely, the liquid conduit may be more hydrophilic or lesshydrophobic than the buffer element. Consequently, the liquid conduitwill have a greater effectiveness to absorb source liquid than thebuffer, and therefore the source liquid will be advantageously conductedalong the conduit and not divert into the buffer unless the conduit isat its maximum capacity and unable to accommodate any more liquid.

Usefully, the capillary force provided by the conduit may be in therange of 2 to 10 times the capillary force provided by the liquidbuffer. For example, the conduit capillary force may be 2 or 3 or 4 or 5or 6 or 7 or 8 or 9 or 10 times greater than the liquid buffer'scapillary force. Larger multiples may also be used, so that the conduithas a capillary force more than 10 times the capillary force of theliquid buffer. Also, smaller values might be used, so that the conduithas a capillary force between 1 and 2 times that of the liquid buffer,such as 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.0 times. These areexample only, however, and other relative values of capillary force thatoffer a higher capillary force in the liquid conduit than in the liquidcapture element are not precluded.

As noted above, the liquid buffer is arranged with respect to theconduit to allow the transfer of liquid between the two components, forexample they are in or near physical contact. The region (portion) orregions where transfer can occur lies between the outlet of thereservoir that feeds liquid to the conduit, and the vaporizer. Inaddition, it is useful if the buffer is located in a region of theelectronic cigarette which is freely connected to the ambientenvironment (surrounding air). This allows the escape of air displacedfrom the buffer when it absorbs liquid, so that absorption can beefficient. The absorption offered by a buffer in an air-tight chamberwill be less effective.

FIG. 5 shows a longitudinal cross-section of part of an exampleelectronic cigarette incorporating a buffer. The Figure is highlyschematic, and outer parts of the electronic cigarette, and the airflowpath through the electronic cigarette are not shown. A tank or reservoir3 for holding source liquid is shown; this provides a supply of liquidfor an atomizer 40 comprising a porous wick 6 and a heating coil 4wrapped around the wick 6. The atomizer is positioned below the tank 3in the depicted orientation. The wick 6 has a u-shape, with first andsecond ends 6 a, 6 b passing through apertures in the base 33 of thetank 3 to receive liquid from the reservoir interior. The heating coil 4is wound around a central portion 6 c of the wick 6 which lies in achamber 7 below the tank 3.

A buffer 50 forms, in this example, side walls of the chamber 7. Also,the buffer 50 is in contact with portions 6 d of the wick 6 which liebetween its ends 6 a, 6 b and its central portion 6 c, in other words,between the tank outlets and the heater 4. The portions 6 d maintaincontact with the buffer 50 over an extended distance, and this contactprovides the required liquid transfer capability for the buffer toabsorb liquid from the wick should the latter become saturated. Notethat close physical contact may be provided, or there may be gap betweenthe wick 6 and the buffer 50 providing that any accumulated liquid isable to bridge the gap and enter the buffer 50 before dripping from thewick 6. Liquid transfer contact may or may not be actual physicalcontact, therefore.

FIG. 6 shows a schematic longitudinal cross-section of part of a furtherexample electronic cigarette incorporating a buffer. In this example,the atomizer 40 is again below the tank 3, and comprises a planar heatermade from a conductive mesh that extends across the atomizer chamber 7so that its two long edges communicate with a pair of conduits 6 thatdeliver liquid from the tank 3. The conduits 6 may be rods or strings ofa porous material, or may be capillary channels (tubes or slots, forexample). An end 6 a, 6 b of each conduit receives liquid from insidethe tank 3. More than two conduits may be used.

A buffer 50 is in liquid transfer contact with each conduit 6, on anopposite side of the conduit to that which communicates with the meshheater 4. The buffer 50 extends the full length of the conduits 6 whichlie outside the tank 3, although this is not essential. This extendedcontact increases the ability of the buffer to collect all excess liquidfrom saturated conduits, however, to reduce the risk of leakage from theelectronic cigarette. In an example where the conduits and the buffercomprise porous materials, the conduit material may have a higherdensity than the buffer material, and/or the conduit material may have alower porosity than the buffer material, as ways to provide the requiredhigher capillary force for the conduits than for the buffer.

Arrangement and positioning of the liquid buffer is not limited to theseexamples, and will depend in part on the configuration of the atomizerand the type and nature of the conduit employed to feed the vaporgenerator. A large volume buffer will be able to accommodate anincreased amount of source liquid so can manage a larger number of, orlonger, leakage episodes. However, a balance will likely be requiredbetween a desirable large buffer capacity, and the available spaceinside the electronic cigarette or a particular desired overall size forthe electronic cigarette. A buffer made from a material with a higherabsorbency will be able to store more liquid, but the absorbency shouldnot compromise the requirement for a lower capillary force for thebuffer compared to the conduit.

A technique to efficiently fit the buffer into the electronic cigaretteis to employ an existing component of the electronic cigarette as thebuffer, by making that component from a suitable absorbent material orforming it to have an absorbent structure. For example, part or all ofthe wall or walls that define the atomizer chamber (that is, the spacein which the atomizer is located and wherein air flows over the vaporgenerator to form the required aerosol for delivery to the user) can beused as the buffer.

FIG. 7 shows a transverse cross-section through an example atomizerchamber formed in this way. The chamber 7 houses the heater 4, which inthis example is a mesh heater as in FIG. 6 . Four conduits 6 deliverliquid to the heater 4 from a tank (not shown); each conduit 6 has oneside in communication with the heater 4 to enable liquid to transfer tothe mesh structure of the heater 4 for heating and vaporization. Thechamber 7 is surrounded by an outer wall formed by the buffer 50. Toachieve this, the buffer 50 may be made from an absorbent material whichis sufficiently rigid to be self-supporting (porous ceramic, or a stifffoam or sponge, for example). Alternatively, a more conventional wallmaterial, such as a rigid plastic, may be provided with capillary holesor channels by molding or machining or other shaping processes to forman absorbent structure. The walls are shaped such that they are closeenough to the sides of the conduits 6 opposite to the heater 4 toprovide the required liquid transfer contact. The sides of the heater 4may be supported by mounting onto the walls. The walls may be formed intwo parts which are joined together to create the chamber 7, as in theFIG. 7 example, or may be made of more or fewer parts. Joins between theparts may provide mounting for the heater.

Wholly or partly surrounding the atomizer chamber with the buffer inthis way provides a large buffer volume with little requirement toincrease the overall size of the electronic cigarette. A similararrangement may be achieved for a non-rigid buffer material, such as asoft foam or sponge, or a wadding. A cage, frame or similar supportingstructure can be placed around the atomizer, and the buffer materialwrapped around the cage.

FIG. 8 shows a transverse cross-section through an example atomizerchamber formed in this way. The chamber 7 accommodates a mesh heater 4and four conduits 6 as before. In this example, though, a cage 51,formed for example of wire (perhaps coated) or molded from plastic,defines the outer perimeter of the chamber 7, and supports the heater 4and/or the conduits 6 (which may also provide some support to eachother). A layer of buffer material 50 is wrapped around the cage 51, andmay be secured in place by adhesive or tying, for example, or may beformed as a tube of material into which the cage 51 and the atomizer isinserted. The cage is formed from struts which are sufficiently thinand/or sufficiently widely spaced to allow close enough contact betweenthe buffer material and the conduits for the required liquid transfercontact.

Use of the buffer to form at least part of the atomizer chamber wall isfurther beneficial in that the buffer is in a position in which it isable to absorb stray source liquid arising from other failure modes,such as spitting of unvaporized liquid from the heater, and condensationof vaporized liquid that has not been successfully taken up in theaerosol stream.

The liquid buffer may be formed from one or more pieces, for example onepiece in contact with one or more conduits or parts of a conduit orconduits, or separate pieces each in contact with a different conduit orconduit part. If more than one piece is used, the pieces may be madefrom different absorbent materials or the same absorbent material.

Some examples discussed above have included more than one conduit (e.g.multiple wicks or capillary channels in a single atomizer). However, ingeneral, herein the term “conduit” should be understood to include bothone conduit and more than one conduit. In other words, it covers boththe singular and the plural.

The liquid buffer may be included as part of an atomizer assemblyintended for incorporation (replaceable or permanent) into a cartomizeror cartridge component for detachable coupling to a battery section toform an electronic cigarette or other vapor provision device (electronicor non-electronic), or may be included directly into such a cartomizeror cartridge component, or may be included directly into an electroniccigarette or other vapor provision device (electronic or non-electronic)that does not comprise detachable or separable components.

The various embodiments described herein are presented only to assist inunderstanding and teaching the claimed features. These embodiments areprovided as a representative sample of embodiments only, and are notexhaustive and/or exclusive. It is to be understood that advantages,embodiments, examples, functions, features, structures, and/or otheraspects described herein are not to be considered limitations on thescope of the invention as defined by the claims or limitations onequivalents to the claims, and that other embodiments may be utilizedand modifications may be made without departing from the scope of theclaimed invention. Various embodiments of the invention may suitablycomprise, consist of, or consist essentially of, appropriatecombinations of the disclosed elements, components, features, parts,steps, means, etc., other than those specifically described herein. Inaddition, this disclosure may include other inventions not presentlyclaimed, but which may be claimed in future.

1. An assembly for a vapor provision device comprising: a reservoir for storing source liquid; a liquid conduit for delivering the source liquid from the reservoir to a vapor generator for vaporizing the source liquid; and a liquid capture element in liquid transfer contact with at least a portion of the liquid conduit between the vapor generator and a part of the liquid conduit that receives liquid from the reservoir, and comprising an absorbent structure providing a higher capillary force than a capillary force of the reservoir.
 2. The assembly according to claim 1, wherein the reservoir is configured to store the source liquid as free-flowing liquid.
 3. The assembly according to claim 1, wherein the reservoir contains absorbent liquid for holding the source liquid within a porous structure.
 4. The assembly according to claim 1, wherein the liquid capture element is located in a region of the vapor provision device which is connected to the ambient environment.
 5. The assembly according to claim 1, wherein the liquid capture element is in contact with the liquid conduit for a full length of the liquid conduit lying outside the reservoir.
 6. The assembly according to claim 1, wherein the absorbent structure provides a lower capillary force that a capillary force of the liquid conduit such that the liquid conduit has a capillary force two or more times greater than the capillary force of the absorbent structure.
 7. The assembly according to claim 1, wherein a further component of the vapor provision device has the absorbent structure so that the further component is employed as the liquid capture element.
 8. The assembly according to claim 7, wherein the absorbent structure is provided by an absorbent material which is self-supporting.
 9. The assembly according to claim 1, further comprising one or more additional liquid conduits, the liquid capture element in liquid transfer contact with at least a portion of the one or more additional liquid conduits.
 10. The assembly according to claim 1, wherein the liquid capture element comprises one piece of absorbent material.
 11. The assembly according to claim 1, wherein the liquid capture element comprises more than one piece of absorbent material.
 12. A cartridge assembly for a vapor provision device comprising the assembly according to claim 1 and the vapor generator for vaporizing the source liquid. 